Roller hemming is a demanding manufacturing process that, even in the age of robotic (robot-supported) industrial processes, can only be reliably implemented with high expenditures of time and costs. However, in many branches of industry, such as the automobile industry, roller hemming is urgently needed for sheet metal forming in serial production. In particular the set-up tasks that precede a stable roller hemming process are very time-consuming. Highly trained and experienced experts are required to adjust the apparatus to the relevant workpiece conditions. The tolerances for form, position and material must be compensated by values learned through experience. Only under such conditions can good results be expected at the end of the process. It is not presently possible to fully compensate for these influencing factors by only using a manipulator and depending on the specifics of the robot's position.
An article by Jens. P. Wulfsberg et al., “Force-regulated Roller Hemming” in: Zeitschrift für wissenschaftlichen Fabrikbetrieb (Journal for Economic Factory Operation), No. 3, 2005, pp. 130-135, describes a force-regulated roller hemming process. In the article, the demanding regulation of an industrial robot for roller hemming is described.
It is an object of the present invention to provide an improved apparatus and an improved method for roller hemming. Cost and time intensive adjustment work for the purpose of setting up a stabile roller hemming process, as well as the influences of the workpiece's position and geometry on the roller hemming process are to be reduced.